but then you also seem to say that using 1066 speed memory with the Core2Quad (1333 fsb) will cause fewer problems.
Certainly not. I said that DDR2-800 causes less problems, regardless of the CPU FSB. Most people who post here about DDR2 memory issues use 1066 memory, not 800. Do yourself a favour and buy G.Skill PI Black DDR2-800: http://www.newegg.com/Product/Product.aspx?Item=N82E168.... They run fine at 800 MHz with 4-4-4-12 timings at 1.9V.